The high and growing costs of fossil fuels and the problem of depletion of these non-renewable resources has led to efforts for improving the efficiency of energy-consuming systems. Internal combustion engines that are extensively used nowadays are one of the main consumers of fossil fuels. Most internal combustion engines produce undesirable pollutants during the combustion process. These undesirable pollutants are produced as a result of incomplete combustion, nitrogen separation, and presence of impurities in the fossil fuels and air. Nitrogen oxides (NOx), unburned hydrocarbons (HC), carbon oxides (COx), sulfur oxides (SOx), soot, and other carbon particles are some of the more impactful pollutants emitted by the internal combustion engines. These pollutants have a negative impact on the environment and cause health problems including causing global warming, air pollution, acid rains, breathing problems, etc.
One possible solution to overcome the incomplete combustion process in the internal combustion engines is the upgrading and improving of fuel compositions. Instead of conducting cost prohibitive research on changing the design of internal combustion engines, additives and catalysts may be mixed in with fuel compositions to alter aspects of the combustion process toward a more complete combustion reaction and more efficient fuel consumption.
Different methods may be used for optimizing fuel consumption and reducing the emission of pollutants. For example, fuel-water emulsions may be prepared by mixing water into a fuel composition, which may improve combustion efficiency and pollutants emission. In another example, nanotechnology may be utilized to enhance the properties of the fuel. Specifically, nano-additives can be used for lowering the amount of harmful pollutants emitted during the process of combustion and simultaneously increase the efficiency of the combustion process. Different types of metal and metal oxide nanoparticles such as platinum, cobalt, radium, iridium, nickel, palladium, copper, silver, gold, zinc, aluminum, alumina, calcium oxide, titanium oxide, zirconium oxide, iron oxides, ruthenium oxide, osmium oxide, cobalt oxide, radium oxide, iridium oxide, nickel oxide, silver oxide, gold oxide, zinc oxide, cerium oxide etc. have been studied as additives in fossil fuels. However, there are some concerns regarding the potential harmful effects of the nanoparticles on human health, especially in case of metal and metal oxide nanoparticles. Since metal and metal oxide nanoparticles may have a poisonous impact on living organisms, there is a need in the art to find other biodegradable nano-additives, such as biodegradable carbon nanoparticles to optimize fuel consumption and reduce the emission of pollutants minimizing any harmful impact on human health and environment.